Some big-cap techs performed well Friday as the new highs list indicated that the stock market today remains healthy. LinkedIn (LNKD) roared ahead 26.39 to 150.48 as volume surged more than eight times its daily average of 1.6 million shares. The big gap-up and solid gains clearly pointed to institutional buying. As of Jan. 15, 4.5 million shares -- or 5% of the float of 86 million shares -- were shorted. Friday's turnover reached 13.9 million